1. Field of the Invention
The present invention relates to a control apparatus for an electronic musical instrument for generating a musical tone based on an input waveform signal.
2. Description of the Related Art
More specifically, the present invention relates to an electronic stringed instrument such as an electronic guitar, a guitar synthesizer, or the like, or other synthesizer type electronic musical instruments and, more particularly, to a control apparatus for an electronic musical instrument which changes the timbre of an output musical tone in accordance with a music performing manner.
Recently, various electronic musical instruments are known wherein a pitch (fundamental frequency) is extracted from an acoustic wave generated according to a human voice or the performance of a conventional musical instrument, and a sound source device comprising an electronic circuit is controlled to artificially produce an acoustic sound such as a musical note.
The following publications disclose such a technique:
(a) U.S. Pat. No. 4,117,757 (issued on Oct. 3, 1978), inventor: Akamatsu.
This patent discloses an electronic circuit for forming a waveform signal in which "1" and "0" sequentially are inverted at positive and negative peak points of and input waveform signal. This waveform signal is converted to a rectangular wave signal, and its frequency corresponds to a pitch of the input waveform signal.
(b) U.S. Pat. No. 4,606,255 (issued on Aug. 19, 1986), inventor: Hayashi et al.
This patent discloses a guitar synthesizer. A pitch is extracted for each string to obtain a corresponding voltage signal, and a musical tone signal is generated by voltage control.
(c) U.S. Pat. No. 4,644,748 (issued on Jan. 6, 1987), inventor: Takashima et al.
This patent discloses a technique for converting an acoustic signal input through a microphone into a digital signal, and extracting a pitch by digital processing.
(d) U.S. Pat. No. 4,688,464 (issued on Aug. 25, 1987), inventor: Gibson et al.
This patent discloses a technique for extracting a pitch in accordance with time intervals crossing three threshold levels, i.e., high, middle, and low threshold levels of an input waveform signal.
(e) Japanese Patent Publication No. 57-37074 (published on Aug. 7, 1982), applicant: Roland Kabushiki Kaisha.
(f) Japanese Patent Publication No. 57-58672 (published on Dec. 10, 1982), applicant: Roland Kabushiki Kaisha.
The contents of these two patents correspond to the above-mentioned patent (a), U.S. Pat. No. 4,117,757, and disclose techniques for generating a rectangular wave having a frequency corresponding to a pitch of an input waveform signal.
(g) Japanese Patent Disclosure (Kokai) No. 55-55398 (disclosed on Apr. 23, 1980), applicant: Toshiba Corp.
This patent application discloses a technique for generating a rectangular wave having a frequency corresponding to a pitch of an input waveform signal as in the patent (a), U.S. Pat. No. 4,117,757.
(h) Japanese Patent Disclosure (Kokai) No. 55-87196 (disclosed on July 1, 1980), applicant: Nippon Gakki Seizo Kabushiki Kaisha.
This prior-art invention discloses a technique for generating a fundamental wave pulse having a period corresponding to a pitch in accordance with an output from a pickup of a guitar, counting the pulse by an interval counter to obtain period data, and converting the period data into digital frequency data.
(i) Japanese Patent Disclosure (Kokai) No. 55-15949 (disclosed on Dec. 11, 1980), applicant: Nippon Gakki Seizo Kabushiki Kaisha.
This prior-art invention discloses a technique wherein when an extracted pitch is not varied, a musical tone is generated. When two adjacent periods substantially coincide with each other, a coincidence signal is generated, and tone generation is started in accordance with the coincidence signal.
(j) Japanese Utility Model Disclosure (Kokai) No. 55-152597 (disclosed on Nov. 4, 1980), applicant: Nippon Gakki Seizo Kabushiki Kaisha.
This prior-art device discloses a technique wherein a vibration of a string is extracted by an optical pickup, and the vibration of the string is excited by a picked-up signal to obtain a vibration sustain effect.
(k) Japanese Utility Model Disclosure (Kokai) No. 55-162132 (disclosed on Nov. 20, 1980), applicant: Keio Gikken Kougyo Kabushiki Kaisha.
This prior-art device discloses a technique wherein a detector detects a next zero-cross point of positive and negative peak points of an input waveform signal, and a flip-flop is set/reset in response to each point detection to generate a frequency signal corresponding to a pitch.
(l) Japanese Patent Publication No. 61-51793 (published on Nov. 10, 1986), applicant: Nippon Gakki Seizo Kabushiki Kaisha.
This patent is a publication of the invention (h) above, and has the same gist as the content of the invention (i) above. That is, digital frequency data is generated upon detection of a substantial coincidence between two adjacent periods.
(m) Japanese Utility Model Publication No. 62-20871 (published on May 27, 1987), applicant: Fuji Roland Kabushiki Kaisha.
This is a Japanese publication corresponding to the invention (b), U.S. Pat. No. 4,606,255.
(n) Japanese Patent Disclosure (Kokai) No. 61-26090 (disclosed on Feb. 5, 1986), applicant: Seikou Denshi Kougyo Kabushiki Kaisha.
This prior-art invention discloses a technique for detecting a pitch from an input waveform signal, sequentially writing the detected pitch in a memory, and obtaining accurate pitch data later by executing an arithmetic operation.
(o) Japanese Patent Disclosure (Kokai) No. 62-163099 (disclosed on July 18, 1987), applicant: Fuji Gen Gakki Seizo Kabushiki Kaisha.
This prior-art invention relates to a guitar controller for a guitar synthesizer, wherein frequency changing methods are switched in accordance with monophonic or polyphonic tones generated. More specifically, when a monophonic tone is generated, a picked-up vibration period is continuously reflected to determine the frequency of the musical sound to be generated. When a polyphonic tone is generated, the vibration period is reflected at chromatic scale steps to determine the same.
Furthermore, the following U.S. patent applications disclose an electronic stringed instrument and the associated electronic equipment are related to the present invention assigned: to the present assignee.
(p) U.S. Ser. No. 112,780 (filed on Oct. 22, 1987), inventor: Uchiyama et al.
This prior-art invention discloses a technique for measuring a time period between positive and negative peak points or between zero-cross points associated with these peak points to extract a pitch of an input waveform signal based on the measured time period, and a technique for performing various control operations in accordance with the obtained pitch.
(q) U.S. Ser. No. 184,099 (filed on Apr. 20, 1988), inventor: Iba et al.
In this prior-art invention, a musical tone parameter such as a timbre is designated by a fret operation and a picking operation of a string. In order to detect an operated fret, a pitch extraction technique, or a fret switch detection technique is used.
(r) U.S. Ser. No. 256,398 (filed on Oct. 7, 1988), inventor: Iba et al.
This prior-art invention discloses a technique for performing musical tone generation control in units of strings, changing characteristics of an output musical tone in accordance with the picking strength of a string, or controlling an effector or pan (sound localization).
(s) U.S. Ser. No. 252,914 (filed on Oct. 3, 1988), inventor: Uchiyama
In this prior-art invention, a pitch extraction circuit comprises a digital circuit in place of a conventional analog circuit, and integration of the electronic circuit can be facilitated.
(t) U.S. Ser. No. 256,400 (filed on Oct. 11, 1988), inventor: Matsumoto
This prior-art invention discloses an electronic apparatus for extracting a pitch from an input waveform signal and generating a musical tone having the corresponding tone pitch, and discloses a technique for changing a tone pitch of an output tone along with a change of the input waveform signal in pitch without accompanying an unnecessary variation in interval.
(u) U.S. Ser. No. 282,510 (filed on Dec. 9, 1988), inventor: Obata
In this prior-art invention, even if a pitch is unstably extracted at the beginning of tone generation, a musical tone having a stable pitch can be generated from the beginning. Start of musical tone generation is chromatically instructed on the basis of a pitch extracted by a pitch extraction system.
(v) U.S. Ser. No. 290,981 (filed on Dec. 28, 1988), inventor: Murata et al.
In this prior-art invention, strings are completely electronically tuned. Before a performance, a reference pitch is determined by plucking at a specific fret, and a tone pitch of a musical tone to be generated is determined on the basis of period data obtained by plucking at a designated fret using the reference pitch.
According to the prior art techniques described above, an intensity of an input waveform signal is detected at its leading edge, and a musical tone is generated while changing a tone volume and timbre of an output tone from a sound source.
Since the tone volume and timbre of a musical tone are changed using one parameter, that is, a signal intensity of the input waveform signal, if the input waveform signal is changed and a tone volume of a musical tone is increased, a timbre sounds hard. That is, these variables are always changed to have a correlation therebetween.
However, when an acoustic guitar or the like is actually plucked to directly produce a tone, even if a picking strength of a string is made constant to keep a constant one volume, a hard timbre is obtained upon picking near a bridge (fixing portion of strings) and a soft timbre is obtained upon picking near a fret (finger board).
Therefore, in the conventional electronic musical instrument wherein a tone volume and a timbre are changed by only a signal intensity, the tone volume and the timbre color cannot be independently controlled by shifting a string picking position. Thus, an abundant performance effect cannot be obtained.